Effect of Oxycombustion Diluents on the Extinction of Nonpremixed Methane Opposed-Jet Flames

ABSTRACT

This study investigates the differences between oxycombustion and conventional air combustion through methane flame extinction measurements and calculations. We report global extinction strain rates for methane with O₂/N₂, O₂/CO₂, and O₂/CO₂/H₂O flames for a range of calculated stoichiometric adiabatic flame temperatures. Tests were performed in a subatmospheric opposed-jet burner, with pre-vaporized water. For a given oxidant diluent, global extinction strain rates increase strongly with increasing flame temperature and with pressure. At a given temperature, the effect of oxidant composition depends on whether dissociation is included in computing the stoichiometric adiabatic flame temperature. When dissociation is included, O₂/CO₂ and O₂/CO₂/H₂O flames are roughly 30% harder to extinguish than O₂/N₂ flames. When dissociation is not included, the oxidant composition has a minimal effect. Calculations with the CHEMKIN suite of programs yield the same ranking of extinction strain rate for the different additives, when stoichiometric adiabatic flame temperature is matched with dissociation included.

Keywords:

• Carbon dioxide
• Counterflow diffusion flame
• Flame extinction
• Opposed-jet diffusion flame
• Oxycombustion

Acknowledgments

The authors with to thank Dr. Rajesh Bhaskaran and Mr. David E. Martin for assistance with error analysis calculations.

Additional information

Funding

The authors gratefully acknowledge the support of the McManus faculty fellowship, Sibley School of Mechanical and Aerospace Engineering, Cornell University.